The present invention is directed to shaving systems and, more particularly, to shaving systems designed to provide uniform shaving forces.
Relatively recent advances in shaving systems have included a variety of dynamic razors wherein one or more of a guard member, seat blade, and cap blade, move in response to forces encountered during shaving. Various systems which have been disclosed permit one or more blades to move in a single plane in response to shaving forces.
One such system described in U.S. Pat. No. 4,586,255 to Jacobson comprises a movable guard bar, and two movable blades, all of which are spring loaded in a supporting structure for movement in response to forces encountered during shaving. The sharpened blades are welded to blade supports which contact upwardly biased leaf springs. The movable guard member and blades are maintained within the supporting structure by metal bands which wrap around the ends of the cartridge. When the movable blades encounter forces during shaving, the blades are urged downwardly into the support structure to less aggressive shaving positions in order to minimize the risk of causing nicks and cuts. In light of the welding steps and the number of separate pieces which must be assembled during the manufacture of this cartridge, it would be desirable to provide a dynamic shaving system which can be manufactured quickly and at relatively low cost.
In this Jacobson design, as well as in numerous other dynamic shaving systems, blades and/or other skin-engaging elements are movably supported by a plurality of resilient spring members. Those skilled in the art will appreciate that any given spring member will exert a certain spring load force on the skin-engaging element to which it is connected. In order to move the skin-engaging element, a force greater than the spring load force must be applied to the skin-engaging element. If the force is applied immediately above the spring member, then a force marginally greater than the spring load force will cause movement of the skin-engaging element. However, in many of the previously suggested designs, skin-engaging elements such as blades are resiliently supported at positions close to either end of the skin-engaging element by at least two spring members. If a force is applied to that skin-engaging element at a midpoint between the spring members, then the force required to cause movement of the skin-engaging element must be greater than the cumulative spring load forces supplied by both of the spring members. Therefore, it will be appreciated that depending upon the point of application of pressure to such a spring loaded skin-engaging element, the forces required to cause movement of that skin-engaging element can vary widely, e.g., by factors of about two.
It would be therefore be desirable to provide greater uniformity to the forces required to move a movable skin-engaging element over the length of that skin-engaging element.
According to one preferred embodiment of the present invention, a shaving system comprises at least one, and preferably a plurality of flexible blades that are movably connected to a support by biasing members. One illustrated embodiment of the present invention comprises a flexible razor head comprising a plurality of blades which are movably connected to a flexible support structure in a manner which permits movement of the blades independent of the flexing of the flexible support. This embodiment of the present invention is designed to avoid the relatively significant load increases exhibited by rigid blade assemblies of the prior art between spring members.
According to another embodiment of the present invention, at least one and most preferably a plurality of blades are connected to a support block which is movably supported within a housing. The blade block is movably supported in a xe2x80x9cfloatingxe2x80x9d manner by biasing members such that at least one blade edge is movable in at least two, and most preferably at least three, different planes in response to forces encountered during shaving. An illustrated embodiment comprises biasing means which bias a blade block vertically, horizontally and laterally. The advantages of this embodiment of the present invention can be embodied in razor heads having rigid or flexible blades.
As used herein, the term xe2x80x9crazor headxe2x80x9d is meant to include cartridges which are designed and manufactured for attachment to a separate razor, as well as the operative portion of a disposable razor wherein the skin-engaging portions are integrally formed with a handle section.